The CLI supports both command abbreviation and command completion. If the keystrokes entered are enough to match a valid command, the CLI displays the remainder of the command syntax when the <Tab> key or space bar is pressed. When typing a command, the <Tab> key or space bar invokes auto-completion. If the keystrokes entered are definite, auto-completion completes the command. If the letters are not sufficient to identify a specific command, pressing the <Tab> key or space bar displays commands matching the letters entered. System commands are available in all CLI context levels.